Autologous fibrin sealant and method for making the same

ABSTRACT

The present relates to an autologous bioadhesive sealant composition or fibrin glue prepared by a two-phase method, wherein all of the blood components for the bioadhesive sealant are derived from a patient to whom the bioadhesive sealant will be applied. A platelet rich plasma and a platelet poor plasma are formed by centrifuging a quantity of anticoagulated whole blood that was previously drawn from the patient. In one embodiment, the platelet rich plasma is divided into two portions. In phase one, a compound that reverses the effect of the anticoagulant is added to the first portion and a clot is allowed to form. The clot is then triturated, and the resulting serum containing autologous thrombin is collected. In phase two, the serum obtained from phase one is mixed with the second portion of the platelet rich plasma to form the bioadhesive sealant of the present invention.

CROSS-REFERENCE TO OTHER APPLICATIONS

This patent application is a divisional of U.S. patent application Ser.No. 10/173,839, filed Jun. 18, 2002 now U.S. Pat. No. 6,830,762, andentitled “Autologous Fibrin Sealant and Method for Making the Same,”which is a continuation of U.S. patent application Ser No. 09/063,338,filed Apr 20, 1998 now U.S. Pat. No. 6,444,228, and entitled “AutologousFibrin Sealant and Method for Making the Same,” which is acontinuation-in-part of U.S. patent application Ser. No. 08/640,278,filed Apr 30, 1996 now abandoned, and entitled “Method for MakingAutologous Fibrin Sealant.”

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to autologous bioadhesive sealantcompositions, and more particularly to a convenient and practicaltwo-phase method for preparing a bioadhesive sealant specifically fromblood components derived from the patient who is to receive thebioadhesive sealant.

2. Description of the State of the Art

When the lining of a blood vessel is damaged, a complex series of eventstakes place which is designed to prevent blood loss and, ultimately, torestore the integrity of the vessel. Although short-livedvasoconstriction and physical factors such as the pressure of extrudedblood on the vessel wall may play some part in haemostasis, the mainfactors in the haemostatic mechanism are platelets and the bloodcoagulation system.

Blood coagulation is the result of the complex interaction of a numberof protein clotting factors through a cascade (FIG. 1). In general,damage to the vascular endothelium exposes subendothelial structures,which attract platelets and induce them to aggregate reversibly. Theprotein thrombin, formed during activation of the coagulation pathwaygenerates insoluble cross-linked fibrils of the protein fibrin andcauses the platelets to aggregate irreversibly. The resultingplatelet-fibrin clot is an effective barrier against loss of blood fromthe vascular system and also serves as a scaffold for subsequent repairof the lining of the blood vessel.

Bioadhesive sealants and fibrin glues represent a relatively newtechnological advance that duplicates the biological process of thefinal stage of blood coagulation. Clinical reports document the utilityof fibrin glue in a variety of surgical fields, such as, cardiovascular,thoracic, transplantation, head and neck, oral, gastrointestinal,orthopedic, neurosurgical, and plastic surgery. At the time of surgery,the two primary components comprising the fibrin glue, fibrinogen andthrombin, are mixed together to form a clot. The clot adheres to thenecessary tissues, bone, or nerve within seconds, but is then slowlyreabsorbed by the body in approximately 10 days by fibrinolysis.Important features of fibrin glue is its ability to: (1) achievehaemostasis at vascular anastomoses particularly in areas which aredifficult to approach with sutures or where suture placement presentsexcessive risk; (2) control bleeding from needle holes or arterial tearswhich cannot be controlled by suturing alone; and (3) obtain haemostasisin heparinized patients or those with coagulopathy. See, Borst, H. G.,et al., J. Thorac. Cardiovasc. Surg., 84:548-553 (1982); Walterbusch, G.J, et al., Thorac Cardiovasc. Surg., 30:234-235 (1982); and Wolner, F.J, et al., Thorac. Cardiovasc. Surg., 30:236-237 (1982).

Despite the effectiveness and successful use of fibrin glue by medicalpractitioners in Europe, neither fibrin glue nor its essentialcomponents fibrinogen and thrombin are widely used in the United States.In large part, this stems from the 1978 U.S. Food and DrugAdministration ban on the sale of commercially prepared fibrinogenconcentrate made from pooled donors because of the risk of transmissionof viral infection, in particular the hepatitis-causing viruses such asHBV and HCV (also known as non A, non B hepatitis virus). In addition,the more recent appearance of other lipid-enveloped viruses such as HIV,associated with AIDS, cytomegalovirus (CMV), as well as Epstein-Barrvirus, and the herpes simplex viruses in fibrinogen preparations make itunlikely that there will be a change in this policy in the foreseeablefuture. For similar reasons, human thrombin is also not currentlyauthorized for human use in the United States. Bovine thrombin, which islicensed for human use in the United States is obtained from bovinesources which do not appear to carry significant risks for HIV andhepatitis, although other bovine pathogens, such as bovine spongiform,encephalitis, may be present.

There have been a variety of methods developed for preparing fibringlue. For example, Rose, et al. discloses a method of preparing acryoprecipitated suspension containing fibrinogen and Factor XIII usefulas a precursor in the preparation of a fibrin glue which involves (a)freezing fresh plasma from a single donor such as a human or otheranimal, e.g. a cow, sheep or pig, which has been screened for bloodtransmitted diseases, e.g. one or more of syphilis, hepatitis oracquired immune deficiency syndrome at about −80° C. for at least about6 hours, preferably for at least about 12 hours; (b) raising thetemperature of the frozen plasma, e.g. to between about 0° C. and roomtemperature, so as to form a supernatant and a cryoprecipitatedsuspension containing fibrinogen and Factor XIII; and (c) recovering thecryoprecipitated suspension. The fibrin glue is then prepared byapplying a defined volume of the cyroprecipitate suspension describedabove and applying a composition containing a sufficient amount ofthrombin, e.g. human, bovine, ovine or porcine thrombin, to the site soas to cause the fibrinogen in the suspension to be converted to thefibrin glue which then solidifies in the form of a gel. See U.S. Pat.No. 4,627,879.

A second technique for preparing fibrin glue is disclosed by Marx inU.S. Pat. No. 5,607,694. Essentially a cryoprecipitate as discussedpreviously serves as the source of the fibrinogen component and thenMarx adds thrombin and liposomes. A third method discussed by Berruyer,M. et al., entitled “Immunization by Bovine Thrombin Used with FibrinGlue During Cardiovascular Operations,” (J. Thorac. Cardiovasc. Surg.,105(5):892-897 (1992)) discloses a fibrin glue prepared by mixing bovinethrombin not only with human coagulant proteins, such as fibrinogen,fibronectin, Factor XIII, and plasminogen, but also with bovineaprotinin and calcium chloride.

The above patents by Rose, et al., and Marx, and the technical paper byBerruyer, et al. each disclose methods for preparing fibrin sealants;however, each of these methods suffer disadvantages associated with theuse of bovine thrombin as the activating agent. A serious and lifethreatening consequence associated with the use of fibrin gluescomprising bovine thrombin is that patients have been reported to have ableeding diathesis after receiving topical bovine thrombin. Thiscomplication occurs when patients develop antibodies to the bovinefactor V in the relatively impure bovine thrombin preparations. Theseantibodies cross-react with human factor V, thereby causing a factor Vdeficiency that can be sufficiently severe to induce-bleeding and evendeath. See, Rapaport, S. I., et al., Am. J. Clin. Pathol., 97:84-91(1992); Berruyer, M., et al., J. Thorac. Cardiovasc. Surg., 105:892-897(1993); Zehnder, J., et al., Blood, 76(10):2011-2016 (1990); Muntean,W., et al., Acta Paediatr., 83:84-7 (1994); Christine, R. J., et al.,Surgery, 127:708-710 (1997).

A further disadvantage associated with the methods disclosed by Marx andRose, et al. is that the cryoprecipitate preparations require a largetime and monetary commitment to prepare. Furthermore, great care must betaken to assure the absence of any viral contaminants.

A final disadvantage associated with the methods previously disclosed isthat while human thrombin is contemplated for use as an activator, humanthrombin is not available for clinical use and there is no evidence thatpatients will not have an antigenic response to human thrombin. Byanalogy, recombinant human factor VIII has been shown to produceantigenic responses in hemophiliacs. See, Biasi, R. de., Thrombosis andHaemostasis, 71(5):544-547 (1994). Consequently, until more clinicalstudies are performed on the effect of human recombinant thrombin onecannot merely assume that the use of recombinant human thrombin wouldobviate the antigenic problems associated with bovine thrombin. A seconddifficulty with thrombin is that it is autocatalytic, that is, it tendsto self-destruct making handling and prolonged storage a problem.

There is still a need, therefore, for a convenient and practical methodfor preparing a bioadhesive sealant composition wherein the resultingbioadhesive sealant poses a zero risk of disease transmission and a zerorisk of causing an adverse physiological reaction.

SUMMARY OF THE INVENTION

Accordingly, this invention provides a method for preparing a completelyautologous bioadhesive sealant composition.

This invention further provides an autologous bioadhesive sealantcomposition wherein the risks associated with the use of bovine andrecombinant human thrombin are eliminated.

This invention further provides an autologous bioadhesive sealantcomposition or fibrin glue prepared by a two-phase method, wherein allof the blood components for the bioadhesive sealant are derived from apatient to whom the bioadhesive sealant will be applied.

Additional advantages and novel features of this invention shall be setforth in part in the description that follows, and in part will becomeapparent to those skilled in the art upon examination of the followingspecification or may be learned by the practice of the invention. Theobjects and advantages of the invention may be realized and attained bymeans of the instrumentalities, combinations, compositions, and methodsparticularly pointed out in the appended claims.

To achieve the foregoing and in accordance with the purposes of thepresent invention, as embodied and broadly described therein, the methodof this invention comprises the formation of an autologous bioadhesivesealant comprising the steps of forming a platelet rich plasma orplatelet poor plasma containing an anticoagulant. The platelet richplasma or platelet poor plasma is then divided into two portions and thefirst portion is restored so that it can coagulate, thus forming a clot.The clot is triturated and the resulting serum is collected. Thebioadhesive sealant composition is then prepared by combining a definedvolume of the second portion of platelet rich plasma or platelet poorplasma with a sufficient volume of serum causing the fibrinogen in thesecond portion of platelet rich plasma or platelet poor plasma to beconverted to fibrin, which then solidifies in the form of a gel.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form a partof the specification illustrate preferred embodiments of the presentinvention, and together with the description, serve to explain theprinciples of the invention.

In The Drawings:

FIG. 1 is a diagrammatic representation of the blood coagulationcascade.

FIG. 2 a is a flow diagram representing the initial portion of themethod of the present invention used to obtain platelet rich plasma andplatelet poor plasma.

FIG. 2 b is a flow diagram representing the final portion of the methodfor preparing the bioadhesive sealant composition of the presentinvention using platelet rich plasma as a starting material.

FIG. 2 c is a flow diagram representing the final portion of the methodfor preparing the bioadhesive sealant composition of the presentinvention using platelet poor plasma as a starting material.

FIG. 3 is a graphic representation of the effect that theserum-to-plasma ratio has on clotting times.

FIG. 4 a is a graphic representation of the relationship betweenclotting time and actual gel time using blood drawn from a donor.

FIG. 4 b is a graphic representation of the relationship betweenclotting time and actual gel time using blood drawn from a donor.

FIG. 5 a graphically represents the effect of calcium addition onclotting times and gel times using blood drawn from a donor.

FIG. 5 b graphically represents the effect of calcium addition onclotting times and gel times using blood drawn from a donor.

FIG. 6 graphically represents the effect of calcium addition on theclotting times of platelet rich plasma and platelet poor plasma.

DETAILED DESCRIPTION OF THE INVENTION

In general, the present invention relates to a two-phase method, shownin FIGS. 2 a, 2 b and 2 c, for forming an autologous bioadhesive sealantcomposition or fibrin glue wherein all of the blood components for thebioadhesive sealant are derived from a patient to whom the bioadhesivesealant will be applied. First, a platelet rich plasma and a plateletpoor plasma are formed by centrifuging a quantity of anticoagulatedwhole blood that was previously drawn from the patient. The plateletrich plasma and platelet poor plasma are then divided into two portions.To the first portion, which is used in phase-one, a compound thatreverses the effect of the anticoagulant is added, and a clot is allowedto form. The clot is then triturated and the resulting serum, containingautologous thrombin, is collected. The serum obtained from phase-one isthen mixed with the second portion of the platelet rich plasma orplatelet poor plasma, used in phase-two, to form the bioadhesive sealantof the present invention.

The method of the present invention for preparing an autologousbioadhesive composition, discussed in further detail below, isrepresented in the flow diagram depicted in FIGS. 2 a, 2 b and 2 c. Themethod of the present invention begins by forming anticoagulated wholeblood 90, which is achieved by collecting a patient's whole blood 80 ina medium containing an anticoagulation agent, such as sodium citrate(citrate) or heparin. The act of drawing blood initiates clottingreactions, and unless something is done to stop the process, a clot willform. The formation of a clot is a multi-step process and several ofthese steps require the presence of calcium ions. By removing thecalcium ions present in whole blood, as is the effect when the blood iscollected in citrate, the blood can be prevented from clotting. Toreinitiate the clot-forming process, calcium is added back into thewhole blood (recalcification). A calcium chelating agent is a chemicalthat reacts with the calcium, present in blood, in such a fashion thatthe calcium can no longer function in blood coagulation. The most commonchelating agent is a salt of citric acid (citrate), since it has thefewest side effects on the components of the clotting system. Bycollecting blood into a medium containing a calcium chelating agent suchas citrate, sample collection and further preparations of the citratedsample can be performed over a time period of up to several hours.

Preferably, the whole blood 80 is collected and mixed with a 3.8%solution of sodium citrate (referred to herein as “citrate collectionmedium”) specifically in a 9:1 ratio of blood to citrate collectionmedium. A 3.8% solution of sodium citrate is prepared by adding 3.8grams of sodium citrate per 100 ml of water. While a 3.8% sodium citratecollection medium is that which is frequently used to collect andpreserve blood, the person skilled in this art will recognize that theratio of sodium citrate to whole blood could be in the range of about10.9-12.9% mMAL, final concentration.

The anticoagulated whole blood 90 is next centrifuged at a rate ofapproximately 20-50 r.c.f.'s (relative centrifugal force) for 10-40minutes, and preferably in a refrigerated centrifuge at 25 r.c.f.'s for20 minutes, resulting in the formation of two liquid phases. The topphase is a platelet rich plasma (PRP) 100, and the bottom phase isanticoagulated whole blood minus the platelet rich plasma 190. Theplatelet rich plasma (PRP) 100 is then gently drawn off and saved in acontainer.

The remaining anticoagulated whole blood minus the platelet rich plasmaphase 190 is further centrifuged at a rate of approximately 3000-4500r.c.f.'s for 15-30 minutes, and preferably in a refrigerated centrifugeat 3850 r.c.f.'s for 20 minutes. This higher rate of centrifugationresults in the red blood cells, white blood cells and platelets beingspun out of the anticoagulated whole blood minus the platelet richplasma phase 190 thereby forming a pellet (not shown) comprisingcellular components which is to be discarded. The resulting plateletpoor plasma (PPP) 200 is then decanted from the pellet and saved in acontainer.

The containers (not shown), which store the platelet rich plasma 100 andplatelet poor plasma 200, may have either wettable surfaces (such as,silica, diatomaceous earth, kaolin, etc.) or non-wettable surfaces (suchas plastic, siliconized glass, etc.). Since surfaces play a role inactivating blood coagulation, the surface of the container chosen tostore either the platelet rich plasma 100 or the platelet poor plasma200 is dependent on whether clot formation is desired quickly or slowly.Chemical activators, such as kaolin, can also be used to speed up theclotting time; however, their subsequent removal would also benecessary. In the preferred embodiment, a glass tube is the preferredcontainer used to collect the platelet rich plasma 100 and the plateletpoor plasma 200.

In the preferred embodiment, according to route 101, the platelet richplasma 100 is divided into two portions. The first portion isapproximately ¼ to ½ of the total volume of platelet rich plasma 100 andis utilized in phase-one to prepare the thrombin, while the secondportion of platelet rich plasma 100 is utilized in phase-two. Once theplatelet rich plasma 100 and the platelet poor plasma 200 are obtained,the preferred methods to obtain the bioadhesive sealant compositions inan expedited manner, that is, in less than two minutes, are detaileddiagrammatically in routes 101 or 201, shown in FIGS. 2 b and 2 c,respectively and discussed in detail below. If, however, a longerclotting time, that is, in a range of two to eight minutes, is desirous,the method to obtain the bioadhesive sealant composition of the presentinvention can proceed along the routes 105 and 205, which are alsodetailed diagrammatically in FIGS. 2 b and 2 c, respectively anddiscussed in detail below.

Phase one according to the preferred embodiment begins by restoring theclot-forming process. To accomplish this, an agent (restoration agent)capable of reversing the effects of the anticoagulation agent is addedback into the first portion of the platelet rich plasma 100. In thepresently preferred embodiment of the invention, the reversal of theanticoagulant is accomplished using calcium chloride. However, anysubstance that is known or found to be functionally equivalent tocalcium chloride, such as, calcium gluconate, in restoring thecoagulation activity of citrated blood may be used in the practice ofthe present invention. Thus, although calcium chloride is the presentlypreferred calcium salt for use in the invention, any calcium salt whichfunctions in a similar manner to calcium chloride may be used in theinvention. Similarly, although many blood coagulation reactions arecurrently believed to require calcium ions as cofactors, any substancethat is known or subsequently found to be functionally equivalent tocalcium in facilitating these coagulation reactions may be used, eitherindividually or in combination with calcium, in the practice of thepresent invention. If the anticoagulation agent used was heparin, thenheparinase would be used to reverse the effect of the anticoagulationagent. The concentration of the restoration agent used to reverse theanticoagulation will depend, in part, upon the concentration of theanticoagulation agent in the platelet rich plasma 100 and thestoichiometry of the chelating and coagulation reactions. However, theconcentration of the restoration agent used to reverse theanticoagulation must be sufficient to achieve clot formation.

Upon restoration of the platelet rich plasma 100 as shown in FIG. 2 b, aclot 110 will naturally form. The resulting clot 110 is then trituratedby high-speed centrifugation, or squeezed through a mesh, thus releasinga serum 120 that comprises thrombin. In the preferred embodiment, theserum 120 is then mixed with the second portion of platelet rich plasma(PRP) 100 to form the bioadhesive sealant composition 130 of the presentinvention in less than two minutes and in quantities sufficient forclinical use.

In an alternative embodiment, serum 120 is mixed with the platelet poorplasma 200 of phase-two thereby forming the autologous bioadhesivesealant composition 140 of the present invention in less than twominutes.

A third embodiment of the present invention, route 105, shown in FIG. 2b, contemplates collecting the original quantity of platelet rich plasma(PRP) 100 derived from the anticoagulated whole blood 90 in a container,having a wettable surface, such as glass. The platelet rich plasma 100is then recalcified and the bioadhesive sealant composition 150 forms.The desired bioadhesive sealant composition 150 will requireapproximately two to eight minutes to form as opposed to less than a twominute formation as was described in the preferred embodiment.

In the fourth embodiment depicted diagrammatically by route 201 in FIG.2 c, the platelet poor plasma 200, rather then the platelet rich plasma100, is divided into two portions, as discussed previously in thepreferred embodiment. The first portion, used in phase-one, which isapproximately ¼ to ½ the original volume is stored in a container havinga wettable surface, then the restoration agent, preferably calciumchloride, is added directly to the platelet poor plasma 200. Surfaceactivation of the restored platelet poor plasma 200 occurs as result ofthe container's surface and a clot forms. The resulting clot istriturated, as described previously, and the serum 220 is collected.Serum 220 is then mixed with the platelet rich plasma 100 of phase-twothereby forming the autologous bioadhesive sealant composition 230.

In the fifth embodiment, serum 220 is mixed with the platelet poorplasma 200 of phase-two thereby forming the bioadhesive sealantcomposition 240 in less than two minutes.

The sixth embodiment follows route 205, shown in FIG. 2 c wherein theoriginal quantity of platelet poor plasma 200, derived from theanticoagulated whole blood minus platelet rich plasma 190, is collectedin a container having a wettable surface, such as glass. The plateletpoor plasma 200 is then recalcified and the bioadhesive sealantcomposition 250 forms.

A seventh embodiment contemplates mixing human recombinantthromboplastin directly with the platelet rich plasma to form abioadhesive sealant composition (not shown). Alternatively, humanrecombinant thromboplastin is utilized to generate thrombin in a smallaliquot of plasma and then the resulting thrombin is combined with theplatelet rich plasma to form a bioadhesive sealant. Thromboplastin maybe later removed by centrifugation.

The tensile strength of the bioadhesive sealant compositions of thepresent invention can be affected by the addition of calcium ions.Consequently, if a stronger bioadhesive sealant composition is desiredusing the methods discussed above and disclosed in routes 101 and 201,in FIGS. 2 b and 2 c, respectively, more calcium ions may be added atthe time the serum is introduced into the platelet rich plasma 100 orthe platelet poor plasma 200. Alternatively, if the method of preparingthe bioadhesive sealant compositions follows routes 105 and 205,depicted in FIGS. 2 b and 2 c, respectively, then calcium ions may beintroduced directly into the platelet rich plasma 100 or the plateletpoor plasma 200 and the bioadhesive sealant compositions 150 and 250,respectively, will form.

As discussed in further detail below, the time period necessary for theformation of the bioadhesive sealant composition of the presentinvention is dependent on the quantity of serum added. A 1:4, 1:2 and3:4 ratio of serum to platelet rich plasma or platelet poor plasmaresults in the formation of the bioadhesive gel composition inapproximately 90, 55 and 30 seconds, respectively. Furthermore, due tothe fact that thrombin is autocatalytic, it is important that the serumbe used within five hours of preparation, preferably within two hoursand ideally immediately. Alternatively, the serum can be chilled orfrozen indefinitely.

The bioadhesive sealant compositions of this invention may be used forsealing a surgical wound by applying to the wound a suitable amountplatelet rich plasma or platelet poor plasma once it has begun to gel.Moreover, due to the fact that the bioadhesive sealant compositions ofthe present invention have been prepared solely from blood componentsderived from the patient that is to receive the bioadhesive sealantthere is a zero probability of introducing a new blood transmitteddisease to the patient.

The methods of the present invention may be further modified so that theformed bioadhesive sealant composition functions not only as ahaemostatic agent, but also as an adjunct to wound healing and as amatrix for delivery of drugs and proteins with other biologicactivities. For example, it is well known that fibrin glue has a greataffinity to bind bone fragments, which is useful in bone reconstruction,as in plastic surgery or the repair of major bone breaks. Consequently,in keeping with the autologous nature of the bioadhesive sealantcomposition of the present invention, autologous bone from a patient canbe ground or made into powder or the like, and mixed into the plateletrich plasma obtained in phase-two of the methods of the presentinvention. Serum comprising thrombin is then mixed in with the plateletrich plasma and bone fragments in an amount sufficient to allow theresulting gel to be applied to the desired locale where it congeals.

In instances where the desired bioadhesive sealant composition of thepresent invention is to further function as a delivery device of drugsand proteins with other biologic activities the method of the presentinvention may be modified as follows. Prior to adding the serumcomprising thrombin obtained in phase-one to the platelet rich plasma ofphase-two, a wide variety of drugs or proteins with other biologicactivities may be added to the platelet rich plasma of phase-two.Examples of the agents to be added to the platelet rich plasma prior tothe addition of the serum include, but are not limited to, analgesiccompounds, antibacterial compounds, including bactericidal andbacteriostatic compounds, antibiotics (e.g., adriamycin, erythromycin,gentimycin, penicillin, tobramycin), antifungal compounds,anti-inflammatories, antiparasitic compounds, antiviral compounds,enzymes, enzyme inhibitors, glycoproteins, growth factors (e.g.lymphokines, cytokines), hormones, steroids, glucocorticosteroids,immunomodulators, immunoglobulins, minerals, neuroleptics, proteins,peptides, lipoproteins, tumoricidal compounds, tumorstatic compounds,toxins and vitamins (e.g., Vitamin A, Vitamin E, Vitamin B, Vitamin C,Vitamin D, or derivatives thereof). It is also envisioned that selectedfragments, portions, derivatives, or analogues of some or all of theabove may be used.

A number of different medical apparatuses and testing methods exist formeasuring and determining coagulation and coagulation-related activitiesof blood. These apparatuses and methods can be used to assist indetermining the optimal formulation of activator, that is, thrombin,calcium and plasma necessary to form the bioadhesive sealant compositionof the present invention. Some of the more successful techniques ofevaluating blood clotting and coagulation are the plunger techniquesillustrated by U.S. Pat. Nos. 4,599,219 to Cooper et al., 4,752,449 toJackson et al., and 5,174,961 to Smith, all of which are assigned to theassignee of the present invention, and all of which are incorporatedherein by reference.

Automated apparatuses employing the plunger technique for measuring anddetecting coagulation and coagulation-related activities generallycomprise a plunger sensor cartridge or cartridges and a microprocessorcontrolled apparatus into which the cartridge is inserted. The apparatusacts upon the cartridge and the blood sample placed therein to induceand detect the coagulation-related event. The cartridge includes aplurality of test cells, each of which is defined by a tube-like memberhaving an upper reaction chamber where a plunger assembly is located andwhere the analytical test is carried out, and a reagent chamber whichcontains a reagent or reagents. For an activated clotting time (ACT)test, for example, the reagents include an activation reagent toactivate coagulation of the blood. A plug member seals the bottom of areagent chamber. When the test commences, the contents of the reagentchamber are forced into the reaction chamber to be mixed with the sampleof fluid, usually human blood or its components. An actuator, which is apart of the apparatus, lifts the plunger assembly and lowers it, therebyreciprocating the plunger assembly through the pool of fluid in thereaction chamber. The plunger assembly descends by the force of gravity,resisted by a property of the fluid in the reaction chamber, such as itsviscosity. When the property of the sample changes in a predeterminedmanner as a result of the onset or occurrence of a coagulation-relatedactivity, the descent rate of the plunger assembly therethrough ischanged. Upon a sufficient change in the descent rate, thecoagulation-related activity is detected and indicated by the apparatus.

Using the methods discussed above, cartridges were assembled with serumobtained from either platelet rich plasma or platelet poor plasma, andCaC12 in the reagent chambers. Clotting time tests were performed by theautomated process with either platelet rich plasma (PRP) or plateletpoor plasma (PPP) dispersed into the reaction chambers of thecartridges. In the first experiment, the results of which arerepresented in FIG. 3, the amount of serum, the type of plasma fromwhich the serum was derived, and the type of plasma the serum was mixedwith were tested to determine the shortest clotting times. The ratios ofserum to platelet rich plasma or platelet poor plasma that were studiedincluded 1:4, 1:2, and 3:4. In the second set of experiments, theresults of which are represented in FIGS. 4 a and 4 b, the relationshipbetween actual gel time for the bioadhesive sealant composition of thepresent was compared to the clotting time in the cartridge, whereinthere is a 0, 30, or 60-minute delay of adding the serum from itsgeneration. The third set of experiments, the results of which arerepresented in FIGS. 5 a and 5 b, studied the effect of calcium additionon actual gel time versus clotting time in the cartridge. The final setof experiments, the results of which are represented in FIG. 6, studiedthe effect of adding calcium on clotting times.

Although clotting times varied among donors, comparisons of clottingtimes for individual donors show significant effects of the serum toplasma ratio and the calcium concentration. For all donors, the shortestclotting times occurred for the 3:4 ratio, with clotting times that were47% shorter than those for the 1:4 ratio. Although the difference inclotting times for the 3:4 ratio and the 1:2 ratio was not statisticallysignificant, the clotting times were consistently shorter using the 3:4ratio for all donors. These results demonstrate that clotting times maybe shortened by increasing the serum to platelet rich plasma ratio.Similarly, clotting times were significantly affected by the amount ofcalcium added, with the shortest clotting times obtained when no calciumwas added, suggesting that the serum contained levels, of calcium thatwere sufficient to recalcify the citrated platelet rich plasma.Preliminary results from the scale-up experiments suggest thatexperimental clotting times in the cartridges correlate with actual geltimes.

The invention is further illustrated by the following non-limitedexamples. All scientific and technical terms have the meanings asunderstood by one with ordinary skill in the art. The specific examplesthat follow illustrate the methods in which the bioadhesive sealantcompositions of the present invention may be prepared in a clinicalsetting and are not to be construed as limiting the invention in sphereor scope. The methods may be adapted to variation in order to producecompositions embraced by this invention but not specifically disclosed.Further, variations of the methods to produce the same compositions insomewhat different fashion will be evident to one skilled in the art.

EXAMPLES

The examples herein are meant to exemplify the various aspects ofcarrying out the invention and are not intended to limit the inventionin any way.

Example 1 Preparation of Bioadhesive Sealant Composition Using PlateletRich Plasma and Serum

10 cc's of platelet rich plasma is added to a sterile glass tubecontaining 0.33 cc's of 10% calcium chloride. A stopper is placed in thetube and the contents are gently mixed and the tube is set aside.Gelling of the contents will occur in two to eight minutes. The gel ispassed to a dry sterile cup where it is squeezed out 4-6 cc's of theserum, produced therefrom, and 1 cc of air is drawn into a syringecontaining 4 cc of platelet rich plasma along with 1 cc of the serum.The bioadhesive sealant composition will gel inside the syringe withinapproximately two minutes. The gel time may be decreased by increasingthe amount of serum added to the platelet rich plasma.

Example 2

10 cc's of whole blood is withdrawn from a patient, placed into asterile glass tube, and allowed to clot naturally. The clot may besubsequently squeezed or centrifuged to release approximately 4-6 cc'sof serum.

An equivalent volume of 10% calcium chloride is then mixed with theserum. 1 cc of this calcified serum is then mixed with 7-8 cc's ofplatelet rich plasma and 2 cc's of air. The resulting bioadhesivesealant will gel in approximately 1-2 minutes.

Example 3

To a sterile glass syringe containing 0.33 cc's of 10% calcium chlorideis added 10 cc's of platelet rich plasma The mixture is allowed to restfor 2 to 8 minutes. Once the gel appears to be appropriately viscous, itmay be applied to the wound site.

The techniques demonstrated in Examples 1 and 2 may be simultaneouslyprepared for (a) an additional source of serum; and (b) to confirmsuccessful coagulation.

The foregoing description is considered as illustrative only of theprinciples of the invention. Furthermore, since numerous modificationsand changes will readily occur to those skilled in the art, it is notdesired to limit the invention to the exact construction and processshown as described above. Accordingly, all suitable modifications andequivalents may be resorted to falling within the scope of the inventionas defined by the claims that follow.

The words “comprise,” “comprising,” “include,” “including,” and“includes,” when used in this specification and in the following claims,are intended to specify the presence of one or more stated features,integers, components, or steps, but they do not preclude the presence oraddition of one or more other features, integers, components, steps, orgroups thereof.

1. A fibrin sealant prepared by the method comprising: contacting afirst portion of a platelet rich plasma, wherein the platelet richplasma is isolated from an individual to whom the fibrin sealant is tobe applied and then separated into the first portion and a secondportion, with a defined volume of a thrombin sample; wherein thethrombin sample is prepared from the second portion of the platelet richplasma by reactivating the second portion to form a clot, andtriturating the clot to form a serum comprising the thrombin sample;preparing the fibrin sealant as a result of the contacting of the firstportion of the platelet rich plasma with the defined volume of thrombin;wherein preparation time of the fibrin sealant is dependent on thedefined volume of the thrombin sample combined with the first portion ofthe platelet rich plasma such that the more defined volume of thethrombin sample is added the quicker the time for preparing the fibrinsealant and wherein the sealant is prepared in under two minutes.
 2. Anautologous bioadhesive sealant prepared by the method consisting of:forming an inactive platelet rich plasma and an inactive platelet poorplasma from a single whole blood sample; separating the inactiveplatelet rich plasma and the inactive platelet poor plasma into arespective first portion and a respective second portion; reactivatingat least one of the first and second portions of the inactive plateletpoor plasma to form a clot; triturating the clot to obtain a serumcomprising autologous thrombin; and combining a defined volume of theserum with at least one of the first and second portions of the plateletrich plasma; preparing the autologous bioadhesive sealant as a result ofcombining; wherein preparation time of the autologous bioadhesivesealant is dependent on the defined volume of the serum combined with atleast one of the first and second portions of the platelet rich plasmasuch that the more defined volume of the serum is added the quicker thetime for preparing the autologous bioadhesive sealant.
 3. The autologousbioadhesive sealant of claim 2, wherein the platelet rich plasma and theplatelet poor plasma each contain sodium citrate.
 4. The autologousbioadhesive sealant of claim 3, wherein reactivation occurs with theaddition of calcium ions.
 5. The autologous bioadhesive sealant of claim2, wherein the platelet rich plasma and the platelet poor plasma eachcontain heparin.
 6. The autologous bioadhesive sealant of claim 5,wherein reactivation occurs with the addition of heparinase.
 7. Theautologous bioadhesive sealant of claim 3, wherein platelet rich plasmaand the platelet poor plasma containing sodium citrate are formed by:collecting said whole blood in a 9:1 ratio of whole blood to 3.8% sodiumcitrate solution forming a citrated blood mixture; and centrifuging thecitrated blood mixture to form a platelet rich plasma and a plateletpoor plasma each containing sodium citrate.
 8. The autologousbioadhesive sealant of claim 2, wherein the whole blood sample isobtained from an individual to whom the autologous bioadhesive sealantis to be applied.
 9. The autologous bioadhesive sealant of claim 2,wherein in the triturating comprises squeezing the clot through a meshto separate the clot from the serum.
 10. The autologous bioadhesivesealant of claim 2, wherein the triturating comprises high speedcentrifugation to separate the clot from serum.
 11. The autologousbioadhesive sealant of claim 2, wherein the serum and the platelet richplasma are mixed in a ratio of 1:4 serum to platelet rich plasma. 12.The autologous bioadhesive sealant of claim 2, wherein the serum and theplatelet rich plasma are mixed in a ratio of 1:2 serum to platelet richplasma.
 13. The autologous bioadhesive sealant of claim 2, wherein theserum and the platelet rich plasma are mixed in a ratio of 3:4 serum toplatelet rich plasma.
 14. The autologous bioadhesive sealant of claim 2,wherein the autologous bioadhesive sealant is produced within 2 minutesof mixing the serum with platelet rich plasma.